This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Memory formation is accomplished through cooperative activity in the hippocampus and the surrounding medial temporal lobe cortex, and the interaction of this complex with neocortex. However, almost nothing is currently known about the neural signals that underlie hippocampal-cortical interaction. Because of its anatomica connectivity, the entorhinal cortex is well-positioned to play a critical role in hippocampal-cortical interaction. The entorhinal cortex is both the main source of cortical input to the hippocampus and the primary target of feedback signals from the hippocampus. Importantly, these connections have laminar specificity such that the superficial layers of the entorhinal cortex project to the hippocampus and the deep layers receive feedback from the hippocampus. The objective of this project has been to to identify the memory-related activity of neurons in superficial and deep layers of the entorhinal cortex. In the past year, we have begun collecting data with a new multi-contact recording electrode. This electrode has 12 contacts, with 300-micron spacing between contacts. Use of this novel technology has allowed us to simultaneously record from all layers of the cortex. Data collected in the past year suggest significant differences in the spectral profile of entorhinal cortex cell layers.